Producing stretch fabric through use of chemical modifiers and a plurality of tension zones

ABSTRACT

The present invention relates to an apparatus wherein a fabric is treated with a shrinking agent and then led through a series of zones under successively increasing warp tension to thereby produce stretch characteristics in the fill direction of the fabric.

Sept. 15, 1970 A. RUNTON PRODUCING STRETCH FABRIC THROUGH USE OFCHEMICALS MODIFIERS AND A PLURALITY OF TENSION ZONES Filed Aug. 5, 1964CONTDOL BOX 2 Sheets-Sheet 1 ZONE TWO ZONE ONE DRYED ZONE FOUR ZONETHQEE INVENTOR. Lasue A. Rum'ou CHEMICAL SOLUTION TANK (COLD) (COLD) 7 ATTORNEY Sept. 15, 1970 RUNTQN 3,528,763

PRODUCING STRETCH FABRIC THROUGH USE OF CHEMICAL MODIFIERS AND APLURALITY OF TENSION ZONES Filed Aug. 5, 1964 2 Sheets-Sheet 3 CONTROLBOX H INVENTOR I LESLIE A. RUNTON I r BY 1. WHLW mmmunmul 3 5 UnitedStates Patent 6 U.S. Cl. 8-125 7 Claims ABSTRACT OF THE DISCLOSURE Afabric is treated with a shrinking agent and led through a series ofzones under successively increasing warp tension to produce stretchcharacteristics in the fill direction thereof.

This invention relates to textiles. More particularly, the inventionrelates to a process and apparatus for the production of stretchablewoven fabrics having the ability to stretch and to recover substantiallycompletely after repeated extension throughout the life of the fabrics.

Fabrics having substantially permanent stretch and recovery propertiesare known. Although these known fabrics have achieved wide commercialacceptance, it is desirable to provide fabrics of this type which haveincreased stretch while maintaining properties of recovery. Currentprocesses and apparatus are suitable for the production of such fabricshaving a stretch factor of just over 20 percent in a filling-wisedirection as well as in a warp-wise direction. However, attempts toproduce fabrics having much more than 20 percent filling-wise stretch bypresent methods and apparatus have generally not been successful orresult in complete breakdown of the fabric by fiber and/ or yarnbreakage. On the other hand, the present process and apparatus providewoven fabrics having filling-wise stretch as high as 50 percent andmore, as well as substantially complete recoverability from repeatedextension throughout the life of the fabrics.

In accordance with the invention there is provided a process forproducing woven fabric having stretch characteristics comprisingdisposing woven fabric having a tension applied to the warp yarnssufficient to straighten the yarns in a warp-wise direction in atreatment zone for a period of time and at a temperature sufiicient tocause deformation of the filling yarns in the fabric, conducting thefabric from the first zone to one or more additional zones whileincreasing the warp tension on the fabric in an amount sufficient totake up any slack which has formed in the warp yarns due to elongationthereof, and maintaining the fabric in the additional zone or zones fora time and at a temperature sufiicient to cause further shrinkage of thefilling yarns and forming fabric having stretch characteristics.

In the practice of the invention, the instant process can be carried outcontinuously, semicontinuously, or as a unitary process and the fabrictreated in accordance therewith exhibits excellent properties of stretchin a filling-wise direction.

Fabric which can be treated in accordance with this invention varieswidely with respect to the materials from which it is made. The fabriccan be made from filamentary synthetic materials such as polyamides,polyesters, acrylics, polyolefins and other suitable syntheticfilamentary materials. The fabric can also be made from natural fiberssuch as wool, cellulosics, such as cotton, or proteinaceous materialsuch as silk and the like. If desirable, fabric processed in accordancewith the invention can be made of a blend of natural and syntheticfibrous materials in either the filling and/or the warp yarns. On theother hand, the filling yarns or the warp yarns can be made entirely ofone type of fiber. In those cases where fabric which contains a blend ofnatural and synthetic fibrous materials is processed in accordance withthe invention, the blend of fibrous materials is one in which theindividual fibrous materials in the blend generally attain stretchcharacteristics when treated under similar conditions. For example, inorder to get maximum benefit of the instant process, fabric containing ablend of polyamide and wool in the filling yarns can have fillingstretch properties imparted thereto by application of heat and moistureat a temperature of about C.

Regardless of the particular fibrous material in fabric processedaccording to the invention, the fabric is woven fabric with the weavebeing sufficiently open to provide space between neighboring yarns.Moreover, the yarns in the fabric can be in a twisted or untwistedstate, depending at least in part on the particular material from whichthe fabric is made. As an example, where a single continuous filamentyarn, such as a polyamide or polyester yarn or the like is beingutilized, twist is not neces sary. On the other hand, where the yarn ismade up of a number of filaments or if it is a spun yarn, at leastenough twist is needed to hold the yarn together and to eliminatefelting and fiber migration. In this con nection Where spun yarns areutilized, twist should be normal to 10 percent above normal. 0n theother hand where a number of continuous filaments are employed to makeup a yarn, a producers twist of approximately onehalf turn to one turnis often sufficient to hold the filaments together.

As mentioned hereinabove the process includes disposing the fabric in aseries of zones, at least two in number. However, the exact number ofzones employed will depend upon the particular fabric being processed.For example, cotton fabric having desirable stretch characteristics isobtained by carrying out the process in an apparatus having four zones.On the other hand, a polyamide fabric having good stretchcharacteristics can be obtained by using only two zones. The exactnumber of treatment zones is dependent upon the ability of the fabricbeing treated to be further elongated in a warpwise direction withoutbreakage. As with the number of zones, the temperature in each zonevaries in accordance with the fiber being processed.

In general, temperatures in a range of about room temperature, that is,about 20 C. to just less than that which will damage the fibrousmaterial present in the fabric being processed are employed in carryingout the process in the various treatment zones. The temperature for aspecific fabric being processed is readily determinable.

Deformation of the yarns in accordance with this invention is to beunderstood to mean both physical and chemical modification thereof,including crimping and the spatial relationship of the filling yarnswith respect to each other and with respect to the warp yarns. Thephysical and chemical deformation is brought about not only by theapplication of warp tension to fabric being processed, but also by thetemperature to which the fabric is subjected and by the optional use ofa chemical agent having the ability to modify as, for example, byshrinking the yarns and fibers to which it has been. applied bymodifying the chemical structure thereof. Moreover, each of thesefactors aid in setting the yarns in their deformed condition.

Any chemical reagent which is compatible with the fabric being processedand which has the ability to modify, as by shrinking or otherwise, andto set the yarns is suitable for use in the practice of this invention.An

excellent reagent which can be utilized when wool fabric is beingprocessed is monoethanolamine sulphite. Other known wool modifyingagents are also suitable. An excellent reagent which can be utilized inthe processing of cotton fabric in accordance with the invention issodium hydroxide. Numerous other reagents are available as will beapparent to those skilled in the art. It is to be noted, however, thatthe particular reagent being utilized should not have an effect on yarnspresent in the fabric other than those which are to be modified by thereagent. In this connection, hot water or steam or the application ofdry heat itself are also excellent reagents for bringing aboutdeformation and setting. Where a chemical modifying agent is used, it isnormally employed in dilute aqueous solutions of about 50 parts water to1 part chemical, about 2 percent solution.

As mentioned hereinabove, the number of zones through which a fabric ispassed will vary depending upon the particular fabric being treated.Wool, for example, can have the desired stretch properties impartedthereto by first treating it with the shrinking agent and then passingit through three zones wherein the temperature is maintained atapproximately 105 C. in each zone, and wherein the warp tension of thefabric is increased by about three percent to four percent between theend of the first zone and the end of the second zone and furtherincreased by a like amount between the second and third zones. On theother hand, excellent stretch properties are imparted to a cotton andDacron blend fabric in a four zone operation wherein the fabric is firstpadded with sodium hydroxide solution and then conducted through thefirst zone under slight tension at a temperature of 20 C., then to asecond zone wherein the temperature remains at about 20 C. and thetension is increased by about two percent to three percent, then to athird zone wherein the temperature is increased to about 105 C. and thetension is further increased by about an additional two to threepercent, and finally to a fourth zone wherein the temperature ismaintained at about 105 C. and the tension is further increased by anadditional two to three percent. Nylon fabric, however, is susceptibleto having stretch properties imparted thereto merely by subjecting it toa temperature of about 140 C., that is, somewhat below the heat settingpoint thereof, and subsequently subjecting the fabric to an increasedtension of about four to six percent at substantially the sametemperature in an additional zone.

Tension placed on a fabric being processed in accordance with thisinvention and which tension is increased as the fabric is led from onezone to another is dependent upon the time and speed with which thefabric is being led from one zone to another of the apparatus. In thiscase it is to be noted, as mentioned hereinbelow, that the tension isincreased by means of a variable speed device, such as a motor or apositive infinitely variable transmission unit which operates rolls orother advancing means in each zone. In order to obtain increasedtension, therefore, the variable speed device of the second zone willoperate at a speed greater than the motor of the first zone, and thespeed of the rolls in each successive zone is increased by an increasein the speed of the variable speed device operating in conjunction withthe rolls of that zone. Generally, the surface speed of the rolls ineach successive zone is increased by about two to six percent. Forexample, if a woolen fabric is being processed at the rate of 94 feetper minute through the first zone, the speed in the second zone isincreased to about 97 feet per minute, and speed in a third or finalzone is increased to about 100 feet per minute. Obviously the surfacespeed of the rolls in each zone which are advancing the fabric throughthe zones are, accordingly, increased by a factor of about 3 percent inthe case illustrated. Since modification of fibers in a fabric takesplace relatively instantaneously once the conditions of temperature andtension are attained in each zone, the time a fabric remains within aparticular zone is not critical, so

long as the total times in all of the zones when accumulated does notexceed a period which will damage the fabric. For wool, the time factoris about 1 min. 10 sec. The particular total time factor for a specificfabric being processed is readily determinable. Consequently, once thedesired conditions of time temperature and tension are attainedin azone, the speed with which the fabric is passed from that zone to thenext successive zone can be as great as is practical under normaloperating conditions. In this case, as pointed out above, the fabric canbe processed as fast as feet per minute and higher, the upper limitationbeing dependent only upon the ability of the fabric and the machinery towithstand the higher speeds without damage thereto, once each successivezone has been brought to a temperature and the required tension isapplied to a fabric being processed therethrough for a sufficient periodof time.

After a fabric has been treated to impart the desired amount of stretchthereto, it is generally led into a drying and/or cooling zone. As apractical matter, although a treated fabric can be permitted to cool ordry in air, it is preferred that positive cooling and drying steps betaken in order to complete the setting. Such measures can includeoptional washing in water or other reagent to remove any excessmodifying reagent which may be retained thereon, or the fabric can bepassed through an atmosphere of conditioned air in order to lower thetemperature thereof. Drying can be carried out at temperatures in arange of C. to C. or less to as high as temperatures just below thatwhich will damage the fabric. Regardless of what positive steps aretaken, the fabric, during this cooling and/or drying treatment, ismaintained in a substantially completely relaxed condition in order topermit additional shrinkage and/or setting to take place.

In order to more properly understand the instant process and apparatususeful for carrying it out, reference is made to the attached drawingswherein:

FIG. 1 is a schematic view of the process as applied to a cotton andDacron blend fabric;

FIG. 2 is a sectional elevation showing one form of apparatus fortreating a fabric according to the invention;

FIG. 2A is a sectional elevation showing the part of the apparatus whichis located after the treatment zones; and,

FIG. 3 is a sectional elevation of a drying and/or cooling meanssuitable for treatment of a fabric which has been processed in thetreatment zones.

Generally, apparatus suitable for carrying out the process comprisesmeans, such as one or more enclosed treatment zones, means for applyingtension to fabric while it is advancing through successive treatmentzones including means for progressively increasing the tension on thefabric, and means for regulating the temperature of the treatment zones.In addition, a preferred apparatus will include means for applyingmodifying agent to a fabric which is subsequently passed through thetreatment zones, and means for washing the fabric after treatment in thezones as well as means for collecting the fabric after it has beentreated and Washed. As an optional part of an apparatus a drying meanscan also be included in carrying out the practice of the invention.Normally the drying means as set forth more fully hereinbelow is locatedafter the washing means through which a fabric passes after it leavesthe treatment zones and before collection thereof on a roll or the like.

Referring more particularly to the drawings, in FIG. 1 the schematicview shows a first station wherein a chemical solution such as sodiumhydroxide is applied to a cotton and Dacron fabric to be processed. Fromthere, the fabric is conducted into the autoclave forming zone onewherein a tension is applied thereto in a warp-wise direction and thefabric is subjected under slight tension to the action of the sodiumhydroxide at a relatively low temperature, that is, about 20 C. Fromzone one, the fabric is then conducted to zone two where the tension isincreased by about two to three percent and the temperature maintainedat 20 C. Thereafter, the fabric is ledinto zone three wherein it issubjected to a further increase of about two to three percent in tensionbut at a temperature of 105 C. Finally, the fabric is conducted to the[fourth treatment zone wherein the tension is further increased by afactor of about two to three percent and the temperature is maintainedat about 105 C. The temperature is normally increased and decreased bythe addition of hot water or steam and cold water. When steam is used,the apparatus is constructed so that the zones are sufficiently sealedfrom the atmosphere to allow enough pressure build-up therein tomaintain steam in that state. After the fabric has been passed throughthe four treatment zones, it is then passed into a drying means wheredrying takes place while the fabric is maintained in a substantiallycompletely relaxed condition. In actual operation, it is to be notedthat before drying, a cotton fabric so treated is also passed through awashing step to remove excess sodium hydroxide therefrom.

With reference to FIGS. 2 and 2A of the drawings, there is shown anapparatus for carrying out the present invention by either a unitary,semicontinuous or continuous process. A strip of fabric 11 is fed from asupply roll by feed rolls 12 and into a J-box 13 where it forms a seriesof loose folds. It is withdrawn from the J-box over a roll 14 and led toa means for applying a modifying agent thereto by introduction betweenguide rolls 15 and thence to a tank 16 which contains a solution ofchemical reagent such as those mentioned hereinabove. The fabric strip11 then passes in a succession of folds under a set of other rolls 17and over a roll 18, the former being immersed in the reagent in tank 16.From the tank 16 the fabric 11 passes over a roll 19 into a tank 20around a roll 21 which is submerged in the solution in the tank, thenceover a roll 22 to the bite of a pair of squeeze rolls 23 and 24 whichremove excess reagent therefrom. A drain returns solution from the tank20 to the tank 16. The upper roll 23 of the squeeze rolls is loaded soas to leave a pickup of about 60 to 80 percent of the fabric Weight inreagent on the fabric. The lower roll 24 dips into the solution in tank20. From the pair of squeeze rolls the fabric passes over a guide roll25 under a control roll 26 or like means upon which tension is placed'by weight 27 regulated through control box 28. Next the fabric ispassed over a guide roll 29 and under a guide roll 30 into the firsttreatment zone 31 equipped with a vent 32 by way of vestibule 33 whichis equipped with a seal 34 to permit entrance of the fabric into thetreatment zone Without affecting the operating conditions therein andalso to minimize the escape of steam if it is to be utilized during theprocess. The control roll 26 or like means actuates control box 28 whichis connected to the drive of the squeeze rolls 23 and 24 in sequence sothat the fabric strip entering the treatment zone is maintained under aconstant tension in the warp-wise direction.

In the treatment zone 31 the fabric passes around a series of upperrolls 35 and a series of lower rolls 36 or like means in the form of aseries of vertical loops. Steam, or cold or hot water is supplied to thezone 31 through supply pipes 37 and 38 equipped with a series of headersor other suitable means.

Treatment zone 31 is enclosed within walls of which end panel 39, topmember 40, separating partition 41 and base member 42, are shown.Separating partition 41 forms a common wall with treatment zone 43 andthe upper end of partition 41 is formed by panel 44 suspended from topmember and equipped with a seal 45 so that as the fabric passes out ofzone 31 to zone 43 the conditions within are not changed. Treatmentzones 46 and 47, located downstream from zones 31 and 43 and which nextreceive the fabric, are enclosed by separating partitions 48, 49 and 50,and base members 51, 52 and 53 respectively. The top member 40 forms acommon panel with these zones and with zone 31. Finally, end panel 54and base member 55 form part of a tank '56 containing water functioningas a seal at the exit end of the treatment zones through which thefabric next passes. The tank is equipped with an exit vestibule 57 andan overflow pipe 58. Located in the tank are guide rolls 59, underwhich, and 60, over which, the exiting fabric passes to the vestibule57.

Treatment zones 43, 46 and 47 are all equipped with upper and lowerrolls 61, 62, 63, 64, 65 and 66 respectively or like means, whichcorrespond to rolls 35 and 36 in zone 31. Zones 43, 46 and 47 also areequipped with supply pipes and headers 67, 68 and '69 below, and 67A,68A and 69 above, connected to sources (not shown) to permit entrance ofsteam or the like into each zone. Moreover panels 70, 71 and 72suspended from top member 40 and equipped with seals 73, 74 and '75serve to isolate each zone from the preceding and subsequent areas andmaintain conditions within each zone. Side panels (not shown) completethe enclosure of the treatment zones and vents (not shown) permit exitof steam or the like there from.

Located above top member 40 is a constant speed main driving motor 76connected to one of upper rolls 35 through a belt drive 77 which passesoutside member 40. Driving motor 76 is also connected through belt drive78 to means such as variable speed device 79, located above member 40and connected to one of the upper rolls 61. Variable speed device 79 isin turn connected to a like device '80 which is then connected to stillanother like unit 81 located above zones 46 and 47 respectively. Devices79, 80 and 81 are connected to the upper rolls 61, 62 and 63 by means ofbelt drives 82, 83 and 84.

As fabric leaves the exit vestibule 57, a guide roll 85 is providedunder which the fabric passes and from which it is led over guide roll86 and thence under a control roll '87 which has tension placed thereonby weight 88 regulated through control box 89 and on its way to thewashing means next passes over guide roll 90 and between rolls 91 undera set of other rolls 92 and over a roll 93, the former being immersed ina washing tank 94. Passing from tank 94 the fabric is led over roll 95and under roll 96, the latter being disposed in a second washing tank97, over a roll 98 to the bite of a pair of squeeze rolls 99' and 100which are adapted to remove the water from the fabric and leave it inonly a moistened condition. From the squeeze rolls the fabric is led tocollecting means and passes over a guide roll 101 between a pair ofrolls 102 and between a pair of reciprocating rolls 103 whichreciprocate through a connection to eccentric 104 and is laid in folds105 below.

The fabric as it is laid in folds on pallet 106 is then transferred to adrying means such as slack loop dryer 107 as shown in FIG. 3. In thoseinstances where the process is being carried out in a continuous orsemicontinuous manner, the pallet 106 may be replaced by a I -box orother suitable arrangement (not shown) from which the fabric iswithdrawn at a slower speed than the speed with which it is beingintroduced in the J-box or the like. This is done in order to maintainthe fabric in an essentially tensionless state and in order to feed itinto the loop dryer in a substantially completely relaxed condition. Thefabric is led over a roll 108 and between driven rolls 109 locatedwithin the walls of the slack dryer and over a plurality of spaced bars110 which are continuously advanced by chain 111 so as to form aplurality of fabric loops 112 which hang from the bars 110 intensionless state. Hot air, or if desirable, cold air is supplied to theslack dryer 107 through passages by way of the floor plate 113 whichcontains passages 114 to permit the hot or cold air to enter.Accordingly the dryer is maintained at a temperature suitable forremoving the remaining liquid from the fabric being dried. In the dryersome additional modification of the fabric takes place although itremains in essentially a smooth condition. Generally a fabric beingprocessed in a dryer can be subjected to a wide temperature range of 100C. or less to as much as C. until the moisture content of the fabric issubstantially completely removed. The best temperature for drying aparticular fabric is readily determinable. If desirable, the temperaturemay be measured by an infra-red sensing device and controlled by meansused in ordinary dryers of this type. From the dryer, the fabric isdelivered between rolls 115 and taken up on a roll 116.

Fabrics treated in accordance with this invention readily lendthemselves to a wide variety of uses. For example,

since woolen fabrics when treated with the disclosed process possessexcellent stretch characteristics, they are useful in the manufacture ofgarments such as mens and boys suits, slacks, sport coats, ladies andchildrens dress fabrics and sportswear, and the like. Such garments dueto treatment in accordance with this invention generally conform to thebody of the wearer with a snug fit and because of the stretchcharacteristics thereof readily expand and contract permitting thewearer to be comfortable while at the same time allowing for freedom ofmovement. In addition, because of the stretch characteristics of agarment manufactured from material treated in accordance with theinvention, flexibility at the elbows and knees overcomes rapiddeterioration to the shape of the garment and to the durability of thewearing qualities.

In addition to the garment field, fabrics treated in accordance with theinvention, such as for example, nylon fabrics, make excellent furniturecoverings and upholstery fabrics which readily conform to the shape ofthe article to which they are applied. Moreover, due to the excellentstretch properties of all fabrics processed in accordance herewith,stretch and recovery is substantially permanent and results in longfabric life. However, in the case of cotton fabrics recovery is improvedby subsequent known processes which will give the cotton a permanentset. Such cotton fabrics are useful in the manufacture of outer garmentsand denims which are particularly useful in the field of sportswear.

The term stretch characteristics as employed throughout thisspecification and in the appended claims is to be understood to meanthat a fabric when treated in accordance with the present invention hasthe ability to be repeatedly extended and it will return to itsnon-extended shape upon release of the stretching force applied theretoin order to bring about extension. In this connection, it is to be notedthat generally fabrics can be extended or stretched up to about 6percent of their original width and/or length. In contrast to this,fabrics treated in accordance with the invention exhibit properties ofstretch as great as 50 percent and more. Fore example, woolen fabricsprocessed in accordance with the invention exhibit properties of stretchin a range of 30 to 45 percent in comparison with a stretch factor ofabout 6 percent exhibited by like woolen fabrics which are not soprocessed, and in comparison to stretch characteristics of about 20percent exhibited by woolen fabrics processed in accordance with knownprocedures for imparting a stretch thereto.

As many apparently widely different embodiments of this invention may bemade without departing from the spirit and scope thereof, it is to beunderstood that the same is not limited to the specific embodimentsthereof except as defined in the appended claims.

What is claimed is:

1. A process for producing a fabric having stretch characteristics inthe fill direction comprising applying to a woven fabric a chemicalreagent capable of causing shrinkage of the filling yarns in said fabricby modifying the chemical structure of said filling yarns, disposingsaid fabric in a first zone under warp tension sufficient to straightenthe warp yarns for a period of time and at a temperature sufiicient tocause shrinkage of the filling yarns by reaction therewith of saidchemical reagent, conducting said fabric from said first zone into atleast one additional zone wherein the warp tension on said fabric isincreased to remove slack resulting from elongation of the warp yarnsand maintaining said fabric therein for a time and at a temperaturesuflicient to cause further shrinkage of the filling yarns by furtherreaction of said chemical reagent with said filling yarns, and Washingsaid fabric to remove excess chemical reagent, thereby developing afabric having stretch characteristics in the fill direction.

2. A process as claimed in claim 1 wherein after said excess is washedfrom said fabric, the fabric is dried while in a substantiallytensionless state.

3. A process as claimed in claim 1 wherein at least one of said zonessaid fabric is contacted with steam.

4. A process as claimed in claim 2 wherein said fill yarns contain wooland said chemical reagent is monoethanolamine sulphite.

5. A process as claimed in claim 3 wherein said fill yarns containcotton and said chemical reagent is sodium hydroxide.

6. A process for producing a fabric having stretch characteristicscomprising contacting a woven fabric consisting mainly of woolen fillingyarns with monoethanolamine sulphite, disposing said fabric in a firstzone under warp tension suflicient to straighten the warp yarns for aperiod of time and at a temperature of about C. in a moist atmosphere tocause deformation of the filling yarns in said fabric, conducting saidfabric from said first zone into a second zone and increasing the warptension on said fabric by an amount sufficient to remove slack thereinresulting from elongation of the warp yarns, maintaining said fabrictherein for a time and at a temperature of about 105 C. in a moistatmosphere to cause further deformation of the filling yarns, conductingsaid fabric from said second zone into a third zone and increasing thewarp tension thereon in an amount sufficient to remove slack thereinresulting from elongation of the warp yarns, maintaining said fabrictherein for a time and at a temperature of about 105 C. in a moistatmosphere to cause further deformation of the filling yarns, removingsaid fabric from the treatment zone, washing excess monoethanolaminesulphite from said fabric and drying said fabric in a substantiallycompletely tensionless state, thereby developing a fabric having stretchcharacteristics.

7. A process for producing a fabric having stretch characteristicscomprising contacting a woven fabric consisting mainly of cotton fillingyarns with sodium hydroxide, disposing said fabric in a first zone underwarp tension sufficient to straighten the warps for a period of time andat a temperature of about 20 C. to cause deformation of the fillingyarns therein, conducting said fabric from said first zone into a secondzone and increasing the warp tension thereon by an amount sufficient toremove slack therein resulting from elongation of the warp yarns andmaintaining said fabric therein for a time and at a temperature of about20 C. to cause further deformation of the filling yarns, conducting saidfabric from said second zone into a third zone and increasing the Warptension thereon by an amount suflicient to remove slack thereinresulting from elongation of the warp yarns and maintaining said fabrictherein for a time and at a temperature of about 105 C. in a moistatmosphere to cause further deformation of the filling yarns, conductingsaid fabric from said third zone to a fourth zone and increasing thewarp tension on said fabric by an amount sufficient to remove slacktherein resulting from elongation of the warp yarns and maintaining saidfabric therein for a time and at a temperature of about 105 C. in amoist atmosphere to cause further deformation of the filling yarns,removing said fabric from the treatment zone, washing excess sodiumhydroxide from said fabric and drying said fabric in a substantiallycompletely tensionless state thereby developing a fabric having stretchcharacteristics.

References Cited UNITED STATES PATENTS 10 FOREIGN PATENTS 148,327 7/1921Great Britain.

GEORGE F. LESMES, Primary Examiner 5 J. CANNON, Assistant Examiner U.S.CLXJR.

